氨基功能氧化石墨烯的制备(DH-GO)及其对废水中Cr(VI) 的去除效果

李明恩; 冯庆革; 林海英; 胡秋艳; 银昱婧; 黄丽欣; 王道铭; 何玉花; 李明治

doi:10.12030/j.cjee.202112041

氨基功能氧化石墨烯的制备(DH-GO)及其对废水中Cr(VI) 的去除效果

广西大学资源环境与材料学院，南宁 530004

广西高校环境保护重点实验室，南宁 530004

作者简介: 李明恩（1995—），男，硕士研究生，1075360224@qq.com

通讯作者: 林海英( 1987—) ，女，博士，讲师，linhaiying@ gxu.edu.cn;

基金项目:

广西自然科学基金面上项目(2020GXNSFAA297011，2018GXNSFBA050008)；国家自然科学基金地区项目(22166006)

中图分类号: X703.1

Preparation of amino functional graphene oxide (DH-GO) and its performance on Cr(VI) removal from wastewater

School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China

Guangxi Universities Key Laboratory of Environmental Protection, Guangxi University, Nanning 530004, China

Corresponding author: LIN Haiying, linhaiying@ gxu.edu.cn ;

摘要: 本研究通过一步合成法，以二氨基胍盐酸盐(DH)为改性剂，以戊二醛为交联剂，制备了氨基功能化氧化石墨烯(DH-GO)。利用单一变量法优化制备条件后，得到最优参数为：改性时间2.5 h，温度35 ℃，pH=10，m(GO∶DH)=1∶5。通过红外和拉曼光谱、扫描电镜等手段对DH-GO进行了形貌的表征和结构的分析，发现改性材料表面因氨基的引入，导致I_D/I_G比值变大，表面负载了许多不规则晶状颗粒。批量吸附实验结果表明：pH对材料的性能影响大，这与材料表面的带电情况、Cr(Ⅵ)的主要存在形态相关；当pH为2时，对Cr(Ⅵ)的吸附容量达到最大。吸附在480 min内可达到平衡，符合拟二级动力学、Langmuir等温模型，主要为单层吸热的化学反应，据此可推测25 ℃时理论最大吸附容量为133.16 mg·g⁻¹。高浓度的${{\rm{NO}}_3^{-}} $和Cl⁻并不干扰吸附的进行，但高浓度的${{\rm{SO}}_4^{2-}} $和${{\rm{PO}}_4^{3-}} $对吸附会有一定的抑制作用。4次循环再生后DH-GO的吸附容量下降了约10%，仍保持着良好的再生性能。吸附机理主要是氨基官能团与水中的H⁺结合并质子化后，与带负电的Cr(Ⅵ)产生静电吸引和反应，同时，羧基和羟基的结合作用、比表面能带来的物理吸附也是另一贡献者。以上研究结果可为GO改性材料应用于含Cr(Ⅵ)废水处理提供参考。

Abstract: The amino-functionalized GO (DH-GO) was prepared by one-step method using diaminoguanidine hydrochloride (DH) as the modifier and glutaraldehyde as the crosslinking agent in this study. After being optimized with the single variable method, the preparation parameters were selected as follows: the modification time of 2.5 h, 35℃, pH 10, m(GO∶DH)=1∶5. The morphology and structure was characterized by Infrared and Raman spectroscopy, Scanning electron microscopy, which indicated that amino groups introduction caused the increase of I_D /I_G value, and many irregular crystalline particles were loaded on the surface. The batch experiments showed that pH had a significant influence on the adsorption capacity of material, which was related to the surface charge of DH-GO and the main existing forms of Cr(VI). At pH 2, the Cr(VI) adsorption capacity of DH-GO reached its peak value. The adsorption reached the equilibrium within 480 min, the process was well fitted with the pseudo-second-order dynamics model and Langmuir isotherm model, indicating the monolayer endothermic chemical reaction occurred, and the maximum adsorption capacity at 25℃ was theoretically estimated to be 133.16mg·g⁻¹. NO₃⁻ and Cl⁻ at high concentrations had slight interference with the adsorption process, while SO₄²⁻ and PO₄³⁻ at high contents had the inhibitory effect to some extent. The adsorption capacity of DH-GO after four cycles of regeneration decreased by about 10%, and maintained a good regeneration performance. The adsorption mechanism was mainly proposed that amino functional groups was firstly protonated by the H⁺ in the solution at pH 2, and then electrostatically attracted and reacted with negatively charged Cr(VI). The bonding of Cr(VI) to carboxyl and hydroxyl groups, and physical adsorption resulting from the high surface area also contributed to adsorption. This is an attempt to modify GO with amino groups, the findings could provide a reference for the application of the modified GO-based materials in Cr(VI) wastewater treatment.

Key words:

T/K

Langmuir

Freundlich

q_m/(mg·g⁻¹)

K_L/(mg·L⁻¹)

R_L

R₁²

K_F

R₂²

298

133.16

0.502 7

0.015 6~0.073 0

0.987 8

1.05

85.62

0.861 3

308

132.63

0.223 4

0.034 6~0.151 9

0.990 3

5.84

60.34

0.961 3

318

160.00

0.799 2

0.009 1~0.167 2

0.994 8

8.03

96.54

0.941 7

吸附剂

q_m/(mg·g^-1)

文献

聚乙烯亚胺改性GO三维复合材料(PEI-GO)

38.20

[24]

铁盐浸渍法合成GO基含铁(GO-Fe)

31.24

[25]

聚间苯二胺接枝的氧化石墨烯(P-GO)

118.34

[26]

氧化石墨烯-壳聚糖复合材料(GO-CS)

67.80

[27]

二氨基胍盐酸盐改性GO(DH-GO)

133.16

本文

氨基功能氧化石墨烯的制备(DH-GO)及其对废水中Cr(VI) 的去除效果

通讯作者: 林海英( 1987—) ，女，博士，讲师，linhaiying@ gxu.edu.cn;

作者简介: 李明恩（1995—），男，硕士研究生，1075360224@qq.com
1. 广西大学资源环境与材料学院，南宁 530004

2. 广西高校环境保护重点实验室，南宁 530004

收稿日期: 2021-12-07

录用日期: 2022-02-18

网络出版日期: 2022-05-23

基金项目:

广西自然科学基金面上项目(2020GXNSFAA297011，2018GXNSFBA050008)；国家自然科学基金地区项目(22166006)

关键词:

Preparation of amino functional graphene oxide (DH-GO) and its performance on Cr(VI) removal from wastewater

Corresponding author: LIN Haiying, linhaiying@ gxu.edu.cn ;

1. School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China

2. Guangxi Universities Key Laboratory of Environmental Protection, Guangxi University, Nanning 530004, China

Received Date: 2021-12-07

Accepted Date: 2022-02-18

Available Online: 2022-05-23

Keywords:

全文HTML

铬被广泛用于皮革、纺织、电镀和其他化学工业，当大量含铬废水排放到水体和土壤中时，会严重造成环境污染和危害人类健康^[1]。铬主要以Cr(Ⅵ)(CrO₄^2-、HCrO₄⁻和Cr₂O₇^2-)和Cr(Ⅲ)的形式存在^[2]。其中Cr(Ⅵ)毒性更强，加上其较好的水溶性会对水环境造成污染，可诱发癌症和呼吸系统疾病^[3]。去除废水中Cr(Ⅵ)的方法包括生物化学法^[4]、吸附法^[5]、离子交换法^[6]、液膜法^[7]、膜过滤法^[8]、电化学法和化学还原沉淀法^[9]。其中，工业中常用的方法为化学还原沉淀法和吸附法。化学还原沉淀法通过加入化学试剂将 Cr(Ⅵ)还原为Cr(Ⅲ)，然后调节pH使其在碱性条件下形成沉淀，进而分离沉淀去除Cr(Ⅵ)。这种处理手段能耗低、操作简便且工艺成熟，但其一般用于处理浓度较大的 Cr(Ⅵ)废水，而且需要多步处理才能达到出水标准，在处理的同时还会产生大量的污泥，易造成二次污染。吸附法主要是利用吸附剂的物理吸附和化学吸附性能去除水中Cr(Ⅵ)，其吸附剂种类多、应用范围广、成本低、吸附容量大、处理效率高、可选择性地去除重金属，并且可以重复使用^[10]，所以利用吸附技术去除废水中的Cr(Ⅵ)的研究变得十分有意义。

氧化石墨烯(graphene oxide , GO)源自于石墨烯合成时衍生的中间产物，是一种新型的材料，含有原子级薄的单分子层，适宜大规模生产，并且具有高比表面积和低质量比容量^[11]。此外，GO表面含有各种碳氧基团(C—OH)、环氧基(C—O—C)、羧基(COOH)和羰基(C=O)，这些结合位点使GO成能与重金属结合^[12]，如Pb(Ⅱ)、Cd(Ⅱ)、Cu(Ⅱ)和Hg(Ⅱ)。然而GO具有易聚集性，含氧官能团数量有限且没有选择性，不足以有效去除水溶液中的重金属离子^[13]，对Cr(Ⅵ)的吸附效果并不好。因此，通过改性剂的搭载制备功能化的GO材料，提高对重金属的吸附性能与选择性，才能提升材料的实际应用性。

众多研究发现，含氨基基团的改性材料对Cr(Ⅵ)有较强的去除能力，其中伯胺或者仲胺基，在酸性条件下容易质子化，从而通过静电引力结合铬酸根，达到净化水质的效果^[14]。KU等^[15]以乙二胺为改性剂，通过有机转化反应和水热法合成了氨基功能化氧化石墨烯复合材料(NH₂-GO/ZnO-ZnFe₂O₄)，在pH为4时，对Cr(Ⅵ)的最大吸附容量为109.89 mg·g⁻¹。GONG等^[16]以乙二胺盐酸盐作为改性剂，采用水热法制备了改性氧化石墨烯(AGO)，在酸性水体中下，AGO主要通过静电引力作用去除Cr(Ⅵ)，同时伴有着部分的Cr(Ⅵ)还原。KIM等^[17]用聚乙烯亚胺为改性剂制备了一种光活性功能化氧化石墨烯(GO@PEI)，能高效吸附/光还原Cr(Ⅵ)。二氨基胍盐酸盐(diaminoguanidine hydrochloride, DH)具有低廉低毒、结构简单的特点，含有大量的—NH₂和—NH基团，对Cr(Ⅵ)有较好的吸附能力^[18]，然而并未见利用DH改性GO材料去除Cr(Ⅵ)的研究，因此，本研究以DH改性GO材料为主体。

本研究以GO为前驱体、戊二醛为交联剂、DH为改性剂，采用一步合成法制备了氨基改性氧化石墨烯(DH-GO)，探讨了不同条件下DH-GO的制备工艺并优化了相关参数；使用扫描电镜(SEM)、红外光谱(FTIR)、X射线衍射(XRD)、拉曼光谱(Raman)、X射线光电子能谱仪(XPS)等表征手段分析了DH-GO的表面形貌、化学官能团、晶型及结构组成特征；探讨了溶液初始pH、投加量、吸附时间、离子强度等对Cr(Ⅵ)去除效果的影响，并采用吸附动力学和等温线模型探明了吸附特性，揭示了DH-GO对水溶液中Cr(Ⅵ)的去除机理。本研究可为含Cr(Ⅵ)废水处理技术选择提供参考。

3. 结论

1)在所制备的氨基功能化氧化石墨烯(DH-GO)中，氨基主要与羧基发生了酰胺化反应、亲核取代反应将DH引入到GO上，然后细小有晶型的颗粒大量沉积于GO表面，增加了其粗糙度和表面能。

2)当pH为2时，Cr(Ⅵ)吸附容量最大，吸附在480 min内可达到平衡，单层的化学吸附占主导。25 °C时，Langmuir拟合的理论最大吸附容量为133.16 mg·g⁻¹，优于其他改性的GO基材料。高浓度的NO₃⁻和Cl⁻对吸附的影响甚微，但高浓度的SO₄^2-和PO₄^3-会有一定的抑制作用，主要是因为竞争吸附。

3)氨基改性基团可成功负载在氧化石墨烯上，表面上的氨基官能团质子化后，与带负电的Cr(Ⅵ)产生静电吸引；同时，羧基和羟基的结合作用、比表面能带来的物理吸附也是另一贡献者。

4) DH-GO经过4次再生循环后，其吸附容量仅下降10%，仍保持着良好的吸附性能。

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